快燃物ACP在丁羟复合固体推进剂中的应用

采用药条燃速仪试验和Ф64mm发动机点火试验,研究了不同含量的快燃物ACP对低、中、高燃速丁羟复合固体推进剂燃烧性能的影响。结果表明,快燃物ACP能明显提高推进剂的燃速,使6．86～15MPa下推进剂的燃速压强指数有明显增大的趋势,在低、中、高燃速推进剂配方中加入质量分数为5％的ACP,15MPa下的燃速分别提高11．3％,82．9％,67．8％。Ф64mm发动机试验表明,含ACP的推进剂在发动机中能够稳定燃烧,发动机p-t工作曲线稳定。获得了ACP使推进剂产生非平行层燃烧从而大幅度提高燃速的初步证据。     

ACP对无烟改性双基推进剂能量和燃烧性能的影响

含ACP的无烟改性双基推进剂能量特性理论计算表明,ACP对推进剂的能量影响较小。研究了不同工艺对含ACP无烟改性双基推进剂燃烧性能的影响。实验结果表明,ACP对压伸工艺制备的推进剂燃速没有显著提高,但能大幅度地提高浇铸无烟改性双基推进剂的燃速。分析了ACP提高无烟改性双基推进剂燃速的作用机理,认为ACP可增加燃烧表面积和热量向燃烧表面积的反馈,使推进剂的燃速大增。     

用ACP提高固体推进剂的燃速

用快燃物ACP提高改性双基推进剂、AP／HTPB复合推进剂和N-15D推进剂的燃速,取得了非常显著的效果。在HMX和RDX改性双基推进剂配方中加入不同粒度不同含量的ACP,推进剂的燃速均能提高,压强指数基本无变化。在AP基复合推进剂配方中加入ACP,其燃速均有不同程度的提高,而且在7～15MPa的压强范围内,压强指数小于0．45。成功地进行Ф64mm发动机试验,并获得稳定的P-t曲线。N-15D推进剂配方的燃速较低,加入ACP后,燃速也有提高,压强指数稍有增大。结果表明,加入ACP后燃速提高效率分别是：HMX改性双基推进剂配方为40．62％,RDX改性双基推进剂配方为38．00％,复合推进剂配方为37．35％,N-15D推进剂配方为9．90％。     

含团聚硼粉富燃料推进剂一次燃烧模型的建立

为研究团聚硼粉对富燃料推进剂燃烧过程中能量释放和燃速特性的影响,结合实验分析建立了基于BDP模型的含团聚硼粉富燃料推进剂一次燃烧的物理和数学模型.该物理模型中,燃烧表面由团聚硼粉、AP和黏合剂的聚集区两部分组成,气相区形成了AP火焰和FF(终焰)聚集区,团聚硼粉中团聚剂参与了PF(初焰)和FF.在假设团聚硼粉为惰性物质基础上,建立了该推进剂的数学燃烧模型.通过AP/HTPB体系、团聚硼粉/AP/HTPB体系的简化与计算,推导出燃速公式中SAP/S的表达式.该模型充分考虑了团聚硼粉体积分数ζ1对推进剂燃面的影响,将硼粉的体积因素引入含硼富燃料推进剂的数学燃烧模型公式,该模型合理解释了这种推进剂的主要燃烧特性.     

燃烧催化剂对含CL-20无烟NEPE推进剂燃烧性能的影响

采用靶线法测试了2~15MPa下含CL-20无烟NEPE推进剂的燃速,通过调节不同种类燃烧催化剂(铅盐、铜盐和炭黑)及其复配催化剂,研究了催化剂对含CL-20无烟NEPE推进剂燃烧性能的影响。分析了含CL-20和催化剂的无烟NEPE推进剂的催化作用机理。结果表明,随着CL-20含量的增加,推进剂的燃速明显增大,当CL-20质量分数为30%时,15 MPa下推进剂的燃速可提高68%。与单组分催化剂和多组分催化剂相比,复配后的双组分燃烧催化剂对推进剂燃速的催化效果最明显,含NTO-Pb/AD-Cu复配催化剂的推进剂在15MPa下的燃速增至25.66mm/s。φ-Pb/乙炔炭黑燃烧催化剂使推进剂在10~15MPa出现平台燃烧,燃速压强指数降至0.22,在2~15MPa下降至0.52。     

纳米催化剂对无烟改性双基推进剂燃烧性能的影响

用均匀设计和多元回归分析方法研究了纳米含能有机铅盐n-ONPP、纳米有机铜盐n-PAC和炭黑复配对无烟改性双基推进剂燃烧性能的影响,并建立了多元回归数学分析模型.结果表明,n-ONPP和n-PAC复配或n-ONPP和炭黑的复配,对提高无烟改性双基推进剂2～6MPa的燃速效果显著,而对提高该推进剂在6～22MPa的燃速效果不明显.但一定量且比例适当的n-ONPP、n-PAC和炭黑复配,能显著提高无烟改性双基推进剂在中低压下的燃速,且在中高压段使推进剂出现平台燃烧,但平台燃烧的压强范围随着催化剂比例的不同而不同.理论分析表明,在2～4MPa,对无烟改性双基推进剂燃速起决定作用的是n-PAC和炭黑;n-ONPP、n-PAC和炭黑三者之间的相互作用对燃速也有一定的作用.在6MPa以上,n-ONPP和n-PAC对燃速起决定作用,炭黑起辅助作用.     

平台双基推进剂铅-铜-炭催化燃速模型

讨论了平台双基推进剂中铅／铜盐以及炭黑所起的作用。提出了催化条件下燃烧初斯产物的解模型，推导出平台推进剂的超速、平台和麦撒各个阶段的燃速公式。计算结果表明，用同一公式计算ＳＱ－５基础配方含不同配比复合催化剂时的燃速，其平均误差小于１０％。     

化学结构对平台推进剂催化燃烧性能影响的理论分析

利用建立的以准一维气相反应流为基础的推进剂稳态燃烧模型,计算了推进剂配方组成对催化燃烧性能的影响,从化学结构的角度分析了平台燃烧的影响因素。由此解释了平台燃烧全过程的化学本质和推进剂燃速压强指数的化学本质,提出了平台推进剂配方和燃速优化设计的原则,为燃速和燃速压强指数的调节提供了理论依据,其结论与国内外实践结果相一致。     

AP-CMDB 推进剂稳态燃烧性能计算研究

建立了一个ＡＰ－ＣＭＤＢ推进剂稳态燃烧模型。该模型可用于ＡＰ－ＣＭＤＢ推进剂和经典双基推进剂燃速特性的模拟计算，其计算结果与文献值相符合，说明该模型是合理、可行的。ＡＰ－ＣＭＤＢ推进剂计算结果表明，ＡＰ粒径减小，ＡＰ含量增加，推进剂燃速升高；而含能粘结剂——ＤＢ母体的含能程度越高，即ＮＧ含量增加，或ＮＣ的硝化度加大，都有利于提高推进剂的燃速。     

RDX-CMDB推进剂燃速温度敏感系数的实验研究

为了揭示RDX-CMDB推进剂中各常见组分对其燃速温度敏感系数的影响规律,制备了一系列含RDX、铝粉及燃烧催化剂的CMDB推进剂样品。采用氮气靶线法测得其在2~14MPa下的燃速温度敏感系数(σp)。讨论了RDX含量、铝粉、燃烧催化剂对RDX-CMDB推进剂燃速温度敏感系数的影响。结果表明,提高工作压强、增加RDX含量、添加燃烧催化剂均有助于降低RDX-CMDB推进剂在一定初始条件下的燃速温度敏感系数。配方中引入铝粉后可降低中低压下RDX-CMDB推进剂的燃速温度敏感系数,且燃速温度敏感系数几乎不随压强变化而变化。选用含邻苯二甲酸铅和没食子酸铋锆作燃烧催化剂,均可在2~10MPa下降低RDX-CMDB推进剂的燃速压强指数,同时降低燃速温度敏感系数。     

Burning Behaviour of ADN Formulations

The application of ADN for an effective oxidizer of propellants and explosives requires a detailed knowledge of the burning behaviour. The physical and chemical mechanisms of the combustion depend on pressure. Especially profiles of temperature and species in the flame are important to design propellant formulation of high performance and low signature of the rocket plume. In the presented study, pure ADN and ADN/paraffin mixtures were investigated as strands in an optical bomb at pressures of 0.5 MPa to 10 MPa. The application of non-intrusive combustion diagnostics for the investigation of fast burning energetic materials allowed the measurement of burning rates and profiles of temperature and gas components at various distances above the burning propellant surface. The burning rate was determined by using a video system and a special frame analysis. The acquisition and analysis of emission spectra in the UV/VIS allowed the investigation of rotational temperatures, the determination of particle temperatures and the identification of transient flame radicals. The vibrational temperatures of final combustion products resulted from band spectra emitted in the near and mid infrared spectral range. Burning rates of 5 mm/s to 70 mm/s were recorded showing a mesa/plateau-effect in the pressure range of 4 MPa to 7 MPa. The UV/VIS spectra indicated an emission from OH, NH and CN radicals. The strong emission of OH bands of the ADN/paraffin mixture allowed the investigation of rotational temperatures with a mean value of 2700 K which is closely below the adiabatic flame temperature of 2950 K. Additionally, one-dimensional intensity profiles of the flame radicals were measured. As combustion end products H₂O, CO, CO₂ and NO were found. NO could only be detected at a distance up to 2 mm above the propellant surface. The measured CO/CO₂ fraction was higher as 10/1. Water could only be detected far above the propellant surface.     

Burning Characteristics of Consolidated Gun Propellants

To improve the combustion behaviors of conventional consolidated propellants, consolidated propellants were prepared using porous propellant grains as fast‐burning filler. The porous propellant grains were prepared by supercritical fluid foaming process and exhibited the high burning rate. The multi‐perforated structure of the consolidated propellants was designed and adopted to obtain high burning progressivity. To investigate the burning characteristics of the consolidated propellants, closed vessel and quenched combustion experiments were carried out. The results show that deconsolidation of the consolidated propellants does not occur, and that the consolidated propellants exhibit high burning rates and high burning progressivities. Besides, the results show that the consolidated propellants burn steadily even at low (−40 °C) and high temperatures (50 °C).     

Measurement and Modelling of Pyrotechnic Time Delay Burning Rates: Application and Prediction of a Fast Burning Delay Composition

A predictive numerical model was implemented for a time delay based on the Si+Pb₃O₄ system. The reaction kinetic parameters were estimated by comparing predicted surface temperature profiles with experimental data acquired with an infrared camera. Fair agreement between the modelled and measured burning rates was achieved. The burning rate is predicted to increase by 9.4 % for every 50 °C increase in ambient temperature. The core diameter was found to have a slightly larger impact on the burning rate than the wall thickness. The effect of using different wall thickness materials was evaluated and indicated that the burning rate is significantly influenced by the wall material when the thermal conductivity is increased and the volumetric heat capacity is reduced. The shape of the combustion front was found to widen with a long tail for materials with a low thermal conductivity and a narrower combustion front with a short tail for materials with high thermal conductivity. Preheating occurred for pyrolytic graphite‐ and diamond‐based elements but no radial combustion was observed. The external heat transfer parameters (convection and radiation) did not affect the burning rate of the fast delay composition. It is concluded that the ambient temperature, volume fraction solids, molar heat of reaction, core and outer diameter are the factors that most significantly influence the burning rate of the Si+Pb₃O₄ composition in long cylindrical elements.     

Solid Propellant Burning Rate From Strand Burner Pressure Measurement

Strand burner pressure–time data are analyzed to determine if the propellant burning rate can be extracted. This approach is based on strand burner pressure–time history that is related to the temperature change due to exothermic reaction heating of chamber gases and gas addition to the chamber by propellant combustion products. In support of this method, chemical equilibrium calculations were made to project product composition, internal energy, and other needed properties. A mathematical model was formulated and solved numerically and the calculated burning rates were compared with the experimental wire‐break time results provided simultaneously and with the propellant manufacturer's results, when available. The comparisons reveal that the approach has merit and that more accurate pressure determination coupled with additional thermochemical information and strand burner gas temperature measurements has the potential to make this approach a viable technique and one that can be applied in conjunction with other burning rate measurements. The proposed method is similar to a well‐developed technique which is commonly applied to ballistic powders but with adjustments for the differences in geometry, pressure, and time of event.     

Burning characteristics of materials

The feasibility of using a dynamic, i.e. multivariable, test procedure instead of the more usual single point tests has been investigated by determining the limiting conditions for burning. The rate of burning and the limiting conditions for flaming and smoldering combustion have been determined over a range of temperatures and oxygen concentrations. Results show that the relative burning rates of materials and also their relative combustion thresholds can alter significantly with changes in the tests environment.     

Effect of the curvature of the burning surface of condensed energetic materials on the burning rate

Combustion of homogeneous condensed energetic materials (CEMs) with a curved burning surface is considered within the framework of the phenomenological theory of unsteady combustion. A dependence of the burning rate on the burning surface curvature is found. It is demonstrated that there exists a limiting surface curvature value above which self-sustained combustion is impossible. This limiting curvature depends on thermophysical and ballistic characteristics of CEMs. The existence of the limiting curvature of the burning surface offers an explanation of the critical conditions of combustion of homogeneous CEMs. Based on this hypothesis, the critical diameters of combustion of several homogeneous CEMs are calculated. The calculated results are in good agreement with available experimental data.     

Investigation of the Burning Behavior of Cryogenic Solid Propellants

Cryogenic Solid Propellant (CSP)‐technology is a new approach to develop more powerful rocket motors. CSPs include the advantages of classical solid propellants to save weight as well as those of a high energy content and safety of modern liquid propellants. The charges consist of liquid and/or gaseous fuels and oxidizers, both frozen. Two main versions of CSP‐technology can be realised: 1. Mono‐CSPs show the burning behavior of solid propellants. Experiments with mono‐CSPs have been carried out under inert pressure conditions in a window bomb. Mono‐CSPs have a stable burning behavior with a constant regression rate which follows the Vieille's law under varying pressure conditions. 2. The advantage of high safety is obtained by assembling oxidizer and fuel in sandwich configurations. The grain geometry governs the burning behavior. Such systems can be externally controlled, e.g. by the heat from a gas generator or they can work self‐sustained. A Rod‐in‐Matrix burner shows self‐sustained combustion in an inert pressure atmosphere with overall burning rates in a similar range as solid rocket propellants which obey also a Vieille‐like pressure law. Disc stack burners have also been investigated, the combustion of which is strongly dependent on the disc thickness. For a short time Mach's nodes have been observed in the exhaust plume of a disc stack burner. Currently, the temperature ranges are limited to the boiling temperature of liquid nitrogen. Therefore, liquid oxidizers like H₂O₂ have been used. However, for the first time a propellant strand of polymer rods embedded in solid oxygen was prepared and burnt. The experiments with CSPs end in the combustion of a small rocket motor showing no serious technical obstacles. Simplified models based on the heat flow equation can simulate the burning characteristics of the frozen energetic materials including phase transitions.     

定容条件下火药实际燃烧规律的数值模拟

为研究火药的实际燃烧规律,建立了定容条件下火药燃烧的修正数学模型,分析了火药实际弧厚的分布及变化、点火不同步和燃速系数变化等因素对火药实际燃烧规律的影响。在此基础上,用考虑综合因素的修正数学模型对定容条件下火药的实际燃烧过程进行了模拟,计算值与实验结果具有较好的一致性,说明修正模型所建立的假设及处理方案是合理的。     

Burning Rate – Pressure Relationship of NG‐PE‐PCP‐based High Energy Propellants

Nitramines are known to produce lower burning rates and higher pressure exponent (η) values. Studies on the burning rate and combustion behavior of advanced high‐energy NG/PE‐PCP/HMX/AP/Al based solid propellant processed by slurry cast route were carried out using varying percentages of HMX and AP. It was observed that propellant compositions containing only AP and Al loaded (total solids 75 %) in NG plasticized PE‐PCP binder produce comparatively lower pressure exponent (η) values similar to AP‐Al filled HTPB based composite propellants. However, energetic propellants containing high level of nitramine (40–60 %) produce high pressure exponent (0.8–0.9) values in the same pressure range. Incorporation of fine particle size AP (ca. 6 μm) and change in its concentration in the propellant composition reduces η value marginally and influences the burning rate. However, such compositions have higher friction sensitivity.     

Simulation of the Erosion Burning of a Granular Propellant

For combustion of axisymmetric propellant grains under blowing conditions, a mathematical model is proposed and numerical simulation is performed. The effects of incoming–flow parameters (velocity, pressure, and temperature) and surface dimensions and geometry on grain–burning rate are studied. Physical patterns of flow around burning propellant grains are presented.